JP4126744B2 - Pump equipment for liquefied gas - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a liquefied gas pump device, and more particularly to a liquefied gas pump device that stores liquefied gas such as liquefied natural gas.
[0002]
[Prior art]
The liquefied gas pump device that transports liquefied gas such as liquefied natural gas includes, for example, a tank built-in type liquefied gas tank submersible pump device used in a liquefied gas tank. In such a liquefied gas pump device, Conventionally, as shown in, for example, JP-A-8-296586, a static pressure bearing and an auxiliary ball bearing are employed.
[0003]
Here, such a conventional liquefied gas pump device will be described with reference to FIG. 8, taking a liquefied gas tank submerged pump device as an example.
[0004]
Reference numeral 1 denotes a liquefied gas tank, 1A denotes a ceiling plate of the gas tank 1, and 2 denotes a pumping pipe suspended in the liquefied gas tank 1. A suction valve 3 is attached to the lower end of the pumped liquid pipe 2 suspended in the liquefied gas tank 1, and the liquefied gas tank submerged pump body 5 is installed on the seat surface 4 of the pumped liquid pipe 2. Reference numeral 6 denotes a plurality of discharge ports provided on the outer periphery of the submerged pump body 5. A head plate 7 having a pump lifting mechanism is provided at the top of the pumping pipe 2, 8 is a lifting wire, 9 is a power supply cable, and 10 is a hoisting machine.
[0005]
The submerged pump body 5 for the liquefied gas tank has a depth of 50 m, for example, by a lifting wire 8 from the head plate 7 to the inside of the pumping pipe 2 vertically suspended from the ceiling plate 1A of the liquefied gas tank 1. It is suspended to the extent that it is seated and installed on the seat surface 4 at the bottom of the pumping pipe 2.
[0006]
The liquefied gas tank submerged pump main body 5 is supplied with power by a power supply cable 9. When the operation of the pump is started, the liquefied gas is sucked from the suction valve 3, and the pressure is increased. As shown by the arrows in the figure, the liquid is discharged from the liquid discharge pipe 2 and is sent out to the discharge pipe 11.
[0007]
Next, as an example of a conventional liquefied gas pump main body, a liquefied gas tank submerged pump main body diagram shown in FIG. 9 will be described.
[0008]
The structure of the liquefied gas tank submersible pump body 5 is such that an inducer 5B, a plurality of impellers 5C, and a submerged motor rotor 5D, which are attached to a pump rotating shaft 5A for improving suction performance, are fixed, and these are integrated structures. It is designed to rotate as a unit. Further, the pump rotating shaft 5A, the inducer 5B, the plurality of impellers 5C, and the submerged motor rotor 5D have a long bearing life and excellent hydrostatic lubrication hydrostatic lubrication (upper hydrostatic bearing 5E, It is supported in the radial direction by a middle hydrostatic bearing 5F and a lower hydrostatic bearing 5G). The upper hydrostatic bearing 5E and the middle hydrostatic bearing 5F are provided with ball bearings (upper ball bearing 5H, middle ball bearing 5I) as auxiliary bearings at the time of starting and stopping the pump. The upper ball bearing 5H includes an installation method in which the inner ring 5H1 is fixed to the pump rotating shaft 5A and a gap is provided on the outer ring 5H2, and an installation method in which the outer ring 5H2 is fixed to the housing 5L1 and a gap is provided on the inner ring 5H1 side. In addition, the inner ball bearing includes an installation method in which the inner ring 5I1 is fixed to the pump rotating shaft 5A and a gap is provided on the outer ring 5I2 side, and an installation method in which the outer ring 5I2 is fixed to the housing 5L2 and a gap is provided on the inner ring 5I1 side. FIG. 9 shows the case where the inner ring is fixed to the pump rotating shaft 5A in both the upper and inner ball bearings.
[0009]
When the method of fixing the inner ball bearing inner ring 5I1 to the pump rotating shaft 5A is taken, the ball bearings 5H, 5I of the ball bearings 5H, 5I are in the normal operation state (the pumping pipe 2 is filled with the pump discharge liquid). Instead, a shaft thrust balancing device 5M composed of a balance disk or the like as shown in, for example, Japanese Patent Publication No. 61-5558 is configured so that the hydrostatic bearings 5E, 5F, and 5G work. As a result, in the normal operation state of the pump, the pump thrust shaft 5A is moved in the axial direction by the function of the axial thrust balancing device 5M, the inner ball bearing 5I is separated from the housing 5L2, and the thrust load applied to the inner ball bearing 5I. Becomes zero. However, when the pump 5 is started, the pump 5 is operated at a discharge pressure considerably lower than a predetermined discharge pressure for several minutes until the inside of the pumping pipe 2 is filled with the discharge liquid. This is because only a slight discharge pressure for pushing up the liquid is sufficient for these several minutes. For this reason, the axial thrust balancing device 5M does not function, and a large thrust load such as the weight of the pump rotor and the downward thrust of the impeller 5C is applied to the inner ball bearing 5I. In particular, when the diameter of the pumping pipe 2 is increased by increasing the capacity of the pump or the like, the time required for the liquid to fill the pumping pipe 2 after starting the pump 5 is further extended. The time during which the thrust load is applied to the center ball bearing 5I is also increased, and the life of the center ball bearing 5I is also shortened. Further, since the discharge pressure of the pump 5 is small for several minutes at the time of starting, the bearing effect of the hydrostatic bearings 5E, 5F, and 5G is small, and the rotary shaft 5A fills the gap between the hydrostatic bearing and the rotary shaft. Swing around. When these states are combined, the rotating shaft 5A performs a precession motion that swings around the middle bearing portion. In this state of precession, a large thrust load is received with the rotating shaft tilted, so that an unstable load is applied to the center ball bearing 5I, and the wear of the center ball bearing 5I is further increased. The service life is reduced. Conventionally, in order to determine the bearing state and life, periodic inspections and the like have been taken to check the disassembly, and there have been cases where sudden ball bearing failures or the like occur during operation due to abnormal wear or the like.
[0010]
[Problems to be solved by the invention]
Although the bearing state and bearing life in the conventional liquefied gas pump device have been determined, in order to reduce costs by simplifying the inspection work, it is required to facilitate the state management of the pump device bearing portion.
[0011]
The present invention provides a sensor for detecting the amount of bearing wear (hereinafter referred to as “bearing wear sensor”) in the pump device, thereby facilitating state management of the pump device, and a sudden ball bearing during operation due to abnormal wear or the like. An object of the present invention is to provide a pump device that is reliable and capable of stable operation, such as detecting a failure of the engine.
[0012]
[Means for solving the problems]
The object is to provide a pump shaft, a drive unit for rotationally driving the pump shaft, an impeller provided at a position below the drive unit along the pump shaft for boosting the sucked liquefied gas, and a radius of the pump shaft. A hydrostatic bearing that is supported in the direction and is self-lubricated, a ball bearing as an auxiliary bearing that is provided close to the hydrostatic bearing and is loaded with a thrust load when the pump is started and stopped, and a normal pump A pump unit for liquefied gas comprising a shaft thrust balancer functioning to balance shaft thrust acting on the pump shaft during operation, wherein the pump device is installed in a liquefied gas tank and sucks and discharges liquefied gas. And a sensor for detecting a change in the axial distance between the rotating body and the fixed body, and the sensor is installed on the fixed body in the vicinity of the ball bearing. The rolling body set up color is achieved by detecting the amount of wear due to the thrust load of the ball bearing by measuring the axial distance between the color at the sensor.
[0013]
In the liquefied gas pump device, when the pump is started, the liquefied gas fills the pumped pipe and reaches the specified discharge pressure, and is applied to the auxiliary bearing for several minutes until the thrust balancer operates. By monitoring the bearing status, it is possible to detect sudden ball bearing failures during operation due to abnormal wear, etc., to improve reliability and to reduce costs by simplifying inspection work. Can do.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0015]
FIG. 1 is a sectional view of a pump main body when the present invention is applied to the submerged pump device for a liquefied gas tank described in FIGS. 8 and 9 as an embodiment of the present invention . FIGS. 2 and 3 are shown in FIG. It is an enlarged view of the middle bearing part of a pump main body . Further, FIGS. 4 through 7, as various embodiments of the present invention, FIG 8 is a diagram of a case of applying the present invention to liquefy gas tank for submersible pump apparatus described in FIG. 9, FIG. 4 of the pump 5 is a sectional view of the upper bearing portion of the pump, FIG. 6 is a sectional view of the upper end portion of the rotating shaft, and FIG. 7 is a sectional view of the lower end portion of the rotating shaft. In the figure, the same reference numerals as those in FIGS. 8 and 9 are the same as those in the prior art, and although not shown in FIG. 1, there are liquefied gas tanks, discharge pipes and the like as in FIG. Not too long.
[0016]
The submerged pump device for a liquefied gas tank according to the present embodiment shown in FIG. 1 includes a pumped pipe 2 suspended in the liquefied gas tank, and a pump body 5 installed on a bottom seat surface 4 of the pumped pipe 2. A suction valve 3 is attached to the bottom of the pumped pipe, from which liquefied gas is sucked and discharged into the solution pipe 2 through a plurality of discharge ports 6 provided on the outer periphery of the pump body 5. The structure of the pump body 5 is such that an inducer 5B, a plurality of impellers 5C, and a submerged motor rotor 5D are fixed to a pump rotating shaft 5A, and these are an integral structure and rotate integrally. . The pump rotating shaft 5A is supported in the radial direction by hydrostatically lubricated hydrostatic bearings (upper hydrostatic bearing 5E, middle hydrostatic bearing 5F, and lower hydrostatic bearing 5G). The upper hydrostatic bearing 5E and the middle hydrostatic bearing 5F are provided with ball bearings (upper ball bearing 5H, middle ball bearing 5I) as auxiliary bearings at the time of starting and stopping the pump. An enlarged view of the vicinity of the middle bearing is shown in FIG.
[0017]
When the inner ring 5I1 of the central ball bearing 5I is fixed to the pump rotating shaft 5A, the inner ball 5I1 is driven by the axial thrust balancing device 5M in the axial direction by the axial thrust balancing device 5M. The bearing 5I is separated (floated) from the housing 5L2, and the thrust load applied to the center ball bearing 5I becomes zero. However, when the pump 5 is started, the pump 5 is operated at a discharge pressure considerably lower than a predetermined discharge pressure for a few minutes until the inside of the pumping pipe 2 is filled with the discharge liquid. Does not function, and a large thrust load such as the weight of the pump rotor and the downward thrust of the impeller 5C is applied to the center ball bearing 5I.
[0018]
An embodiment in such a pump structure will be described.
FIG. 2 shows an example in which a bearing wear sensor 5J is installed in the middle bearing portion. FIG. 2 shows a case where the inner ring 5I1 of the center ball bearing 5I is fixed to the pump rotating shaft 5A. Bearing wear sensor 5J measures the distance between the anti-scattering color 5 K and the sensor 5J, than this calculated amount of wear of the bearing. As the bearing wear progresses, the weight of the pump rotating body is added to the ball bearing inner ring 5I1 fixed to the rotating shaft 5A when the pump is stopped. Therefore, as shown in FIG. It sinks low according to. Accordingly Color 5 K, narrowing also the distance between the sensor 5 J, it is possible to know the amount of wear of the bearing from the amount of change.
[0019]
Next, FIG. 4 shows a case where a method of fixing the inner ball bearing outer ring 5I2 to the housing 5L2 is taken. Similarly, the amount of bearing wear can be determined by measuring the amount of depression of the inner ring 5I1, that is, the change in the distance between the collar 5M and the sensor 5J.
[0020]
As described above, the present invention can be applied to either an installation method for fixing the inner ring 5I1 of the inner ball bearing 5I to the pump rotating shaft 5A or an installation method for fixing the outer ring 5I2 to the housing 5L2.
[0021]
In the embodiment, the anti-scattering collar 5K is used for distance measurement. However, a flat plate or the like may be used as long as the bearing wear amount is measured in the embodiment. Further, these collars, flat plates, etc. may be fixed to the place to be installed with bolts or the like, or may be manufactured integrally with the parts to be installed. Speaking along the example shown in FIG. 2, a color 5 K may be installed in a ball bearing inner race 5I1 and the rotating shaft 5A, it may be manufactured integrally with the ball bearing inner ring 5I1 and the rotating shaft 5A.
[0022]
The installation position of the bearing wear sensor 5J may be any place where the axial distance between the pump rotating body and the fixed body can be measured. FIG. 5 shows an example in which the bearing wear sensor 5J is installed in the upper bearing portion. As wear progresses, the rotating body settles according to the amount of wear when the pump is stopped. Therefore, the distance between the collar 5K and the sensor 5J in FIG. 5 increases, and the amount of wear of the bearing can be known from the amount of change. As described above, the upper ball bearing 5H includes an installation method for fixing the inner ring 5H1 to the pump rotating shaft 5A and an installation method for fixing the outer ring 5H2 to the housing 5L1. FIG. 5 shows the former, but the present invention can be applied to either of the installation methods as in the example of the center ball bearing 5I.
[0023]
Next, FIG. 6 shows an example in which the bearing wear sensor 5J is installed at the upper end of the shaft. When the rotating body sinks as described above, the distance between the rotating shaft 5A and the sensor 5J in FIG. 6 increases, and the amount of wear of the bearing can be known from the amount of change.
[0024]
FIG. 7 shows an example in which the bearing wear sensor 5J is installed at the lower end of the shaft. When the rotating body settles as described above, the distance between the rotating shaft 5A and the sensor 5J in FIG. 7 is reduced, and the amount of wear of the bearing can be known from the amount of change.
[0025]
In addition, as for the measurement at the shaft upper end portion and the shaft lower end portion as shown in FIGS. 6 and 7, a collar, a flat plate, or the like may be used as long as the bearing wear amount is measured in the embodiment. In addition, the collar, the flat plate, etc. may be fixed to the place to be installed with a bolt or the like in the upper bearing portion, the shaft upper end portion, the shaft lower end portion or the like, or may be manufactured integrally with the parts to be installed.
[0026]
According to the present embodiment, the bearing wear sensor 5J is installed in the pump device, and the amount of wear of the ball bearing is monitored by this, thereby reducing the cost by simplifying the inspection work and suddenly during operation due to abnormal wear or the like. It can contribute to improving the reliability of the pump device, such as detecting a failure of a simple ball bearing.
[0027]
As described above, the present invention can naturally be applied to a pot type liquefied gas pump in which a pump is housed in a suction casing in the case of another type of liquefied gas pump device. Moreover, it is effective not only for liquefied gas but also for a pump that handles a low-temperature liquid or the like.
[0028]
【The invention's effect】
As described above, according to the present invention, the bearing wear sensor is installed in the pump device, and the wear amount of the bearing is detected, thereby facilitating the state management of the pump device bearing portion and improving the reliability. Can do. In addition, the cost can be reduced by simplifying the inspection work. As a result, stable operation of the liquefied gas pump device can be achieved.
[Brief description of the drawings]
FIG. 1 is a sectional view of a liquefied gas pump main body showing an embodiment of the present invention.
2 is an enlarged view of a pump shaft middle bearing portion shown in FIG. 1. FIG.
3 is an enlarged view of a pump shaft middle bearing portion shown in FIG. 1. FIG.
FIG. 4 is an enlarged view of a pump shaft middle bearing portion showing another embodiment of the present invention.
FIG. 5 is an enlarged view of a pump shaft upper bearing portion showing still another embodiment of the present invention.
FIG. 6 is an enlarged view of a pump shaft upper end portion showing still another embodiment of the present invention.
FIG. 7 is an enlarged view of a lower end portion of a pump shaft showing still another embodiment of the present invention.
FIG. 8 is an overall view of a submersible pump device for a liquefied gas tank.
FIG. 9 is a sectional view of a conventional submerged pump main body for a liquefied gas tank.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 liquefied gas tank 1A tank ceiling board 2 liquid pump 3 suction valve 4 seat surface 5 liquefied gas pump body 5A rotary shaft 5B inducer 5C impeller 5D submerged motor rotor 5E upper static pressure bearing 5F middle static pressure bearing 5G lower static pressure Bearing 5H Upper auxiliary ball bearing 5H1 Upper auxiliary ball bearing inner ring 5H2 Upper auxiliary ball bearing outer ring 5I Middle auxiliary ball bearing 5I1 Middle auxiliary ball bearing inner ring 5I2 Middle auxiliary ball bearing outer ring 5J Bearing wear sensor 5K Anti-scattering collar 5L1 Housing 5L2 Housing 5M Shaft thrust Equilibrium device 6 Pump discharge port 7 Head plate 8 Lifting wire 9 Feeding cable 10 Winding machine 11 Discharge pipe

Claims (1)

A pump shaft, a drive unit for rotationally driving the pump shaft, an impeller provided at a position below the drive unit along the pump shaft for boosting the sucked liquefied gas, and supporting the pump shaft in the radial direction. A hydrostatic lubricated hydrostatic bearing, a ball bearing as an auxiliary bearing provided close to the hydrostatic bearing and loaded with a thrust load when the pump is started and stopped, and a pump shaft during normal operation of the pump In a liquefied gas pump device comprising a shaft thrust balance device that functions to balance the shaft thrust acting on the liquefied gas, installed in the liquefied gas tank and sucking and discharging the liquefied gas,
The pump device has a sensor for detecting a change in the axial distance between the rotating body and the fixed body, and the sensor is installed on the fixed body in the vicinity of the ball bearing, and rotates in the vicinity of the ball bearing. A liquefied gas pump device characterized in that a collar is installed on the body, and the amount of wear due to the thrust load of the ball bearing is detected by measuring the axial distance from the collar with the sensor .

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